1 //===- lib/Linker/LinkArchives.cpp - Link LLVM objects and libraries ------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains routines to handle linking together LLVM bytecode files,
11 // and to handle annoying things like static libraries.
13 //===----------------------------------------------------------------------===//
15 #include "llvm/Linker.h"
16 #include "llvm/Module.h"
17 #include "llvm/ModuleProvider.h"
18 #include "llvm/ADT/SetOperations.h"
19 #include "llvm/Bytecode/Reader.h"
20 #include "llvm/Bytecode/Archive.h"
21 #include "llvm/Config/config.h"
26 /// GetAllUndefinedSymbols - calculates the set of undefined symbols that still
27 /// exist in an LLVM module. This is a bit tricky because there may be two
28 /// symbols with the same name but different LLVM types that will be resolved to
29 /// each other but aren't currently (thus we need to treat it as resolved).
32 /// M - The module in which to find undefined symbols.
35 /// UndefinedSymbols - A set of C++ strings containing the name of all
36 /// undefined symbols.
39 GetAllUndefinedSymbols(Module *M, std::set<std::string> &UndefinedSymbols) {
40 std::set<std::string> DefinedSymbols;
41 UndefinedSymbols.clear();
43 // If the program doesn't define a main, try pulling one in from a .a file.
44 // This is needed for programs where the main function is defined in an
45 // archive, such f2c'd programs.
46 Function *Main = M->getMainFunction();
47 if (Main == 0 || Main->isExternal())
48 UndefinedSymbols.insert("main");
50 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
53 UndefinedSymbols.insert(I->getName());
54 else if (!I->hasInternalLinkage()) {
55 assert(!I->hasDLLImportLinkage()
56 && "Found dllimported non-external symbol!");
57 DefinedSymbols.insert(I->getName());
60 for (Module::global_iterator I = M->global_begin(), E = M->global_end();
64 UndefinedSymbols.insert(I->getName());
65 else if (!I->hasInternalLinkage()) {
66 assert(!I->hasDLLImportLinkage()
67 && "Found dllimported non-external symbol!");
68 DefinedSymbols.insert(I->getName());
72 // Prune out any defined symbols from the undefined symbols set...
73 for (std::set<std::string>::iterator I = UndefinedSymbols.begin();
74 I != UndefinedSymbols.end(); )
75 if (DefinedSymbols.count(*I))
76 UndefinedSymbols.erase(I++); // This symbol really is defined!
78 ++I; // Keep this symbol in the undefined symbols list
81 /// LinkInArchive - opens an archive library and link in all objects which
82 /// provide symbols that are currently undefined.
85 /// Filename - The pathname of the archive.
88 /// TRUE - An error occurred.
89 /// FALSE - No errors.
91 Linker::LinkInArchive(const sys::Path &Filename) {
93 // Make sure this is an archive file we're dealing with
94 if (!Filename.isArchive())
95 return error("File '" + Filename.toString() + "' is not an archive.");
97 // Open the archive file
98 verbose("Linking archive file '" + Filename.toString() + "'");
100 // Find all of the symbols currently undefined in the bytecode program.
101 // If all the symbols are defined, the program is complete, and there is
102 // no reason to link in any archive files.
103 std::set<std::string> UndefinedSymbols;
104 GetAllUndefinedSymbols(Composite, UndefinedSymbols);
106 if (UndefinedSymbols.empty()) {
107 verbose("No symbols undefined, skipping library '" +
108 Filename.toString() + "'");
109 return false; // No need to link anything in!
113 std::auto_ptr<Archive> AutoArch (
114 Archive::OpenAndLoadSymbols(Filename,&ErrMsg));
116 Archive* arch = AutoArch.get();
119 return error("Cannot read archive '" + Filename.toString() +
122 // Save a set of symbols that are not defined by the archive. Since we're
123 // entering a loop, there's no point searching for these multiple times. This
124 // variable is used to "set_subtract" from the set of undefined symbols.
125 std::set<std::string> NotDefinedByArchive;
127 // While we are linking in object files, loop.
130 // Find the modules we need to link into the target module
131 std::set<ModuleProvider*> Modules;
132 if (!arch->findModulesDefiningSymbols(UndefinedSymbols, Modules, &ErrMsg))
133 return error("Cannot find symbols in '" + Filename.toString() +
136 // If we didn't find any more modules to link this time, we are done
137 // searching this archive.
141 // Any symbols remaining in UndefinedSymbols after
142 // findModulesDefiningSymbols are ones that the archive does not define. So
143 // we add them to the NotDefinedByArchive variable now.
144 NotDefinedByArchive.insert(UndefinedSymbols.begin(),
145 UndefinedSymbols.end());
147 // Loop over all the ModuleProviders that we got back from the archive
148 for (std::set<ModuleProvider*>::iterator I=Modules.begin(), E=Modules.end();
151 // Get the module we must link in.
152 std::auto_ptr<Module> AutoModule( (*I)->releaseModule() );
153 Module* aModule = AutoModule.get();
155 verbose(" Linking in module: " + aModule->getModuleIdentifier());
158 if (LinkInModule(aModule))
159 return error("Cannot link in module '" +
160 aModule->getModuleIdentifier() + "': " + Error);
163 // Get the undefined symbols from the aggregate module. This recomputes the
164 // symbols we still need after the new modules have been linked in.
165 GetAllUndefinedSymbols(Composite, UndefinedSymbols);
167 // At this point we have two sets of undefined symbols: UndefinedSymbols
168 // which holds the undefined symbols from all the modules, and
169 // NotDefinedByArchive which holds symbols we know the archive doesn't
170 // define. There's no point searching for symbols that we won't find in the
171 // archive so we subtract these sets.
172 set_subtract(UndefinedSymbols, NotDefinedByArchive);
174 // If there's no symbols left, no point in continuing to search the
176 if (UndefinedSymbols.empty())